1. Field of the Invention
The present invention relates to decorative panels and, more particularly, to an abrasion resistant laminate for use as a decorative panel. The abrasion resistant laminate is preferably a low pressure laminate. The laminate has preferably a printed decorative pattern, but can have a solid color. In addition, the present invention relates to a process for manufacturing such an abrasion-resistant laminated panel.
2. Description of Related Art
Decorative panels have been used to produce kitchen and bath cabinets, office furniture, store fixtures and recreational furniture. For many years, decorative furniture components were made by laminating a high pressure laminate to wood panel substrate, such as plywood or particleboard. The glue line lamination occurred either before or after the furniture was assembled. Within the past twenty-five years, a low pressure laminate has become available. Such low pressure laminates are manufactured by directly laminating the decorative sheet to the substrate under heat and pressure.
Conventionally, high pressure decorative laminates have been made by stacking and curing, under heat and pressure, a plurality of layers of paper impregnated with synthetic thermosetting resins. Normally, the assembly consists of three to eight core sheets. The assembly has from the base upward (1) phenolic resin impregnated Kraft paper, (2) a decor or decorative sheet impregnated with melamine resin, and (3) for printed patterns, an overlay sheet which, in the laminate, is almost transparent and provides protection for the decor sheet.
Some improvements are described in U.S. Pat. No. 4,255,480 and U.S. Pat. No. Re. 32,152, both to Scher, et al. For example, U.S. Pat. No. 4,255,480 discloses manufacturing decorative laminates having an ultra-thin, protective coating deposited as the uppermost layer of the decor sheet to enhance abrasion-resistant properties. The decor sheet is coated with an ultra-thin layer of a mixture of an abrasion-resistant hard mineral and a binder material. The hard mineral has a particle size of 20 to 50 microns.
Background patents of interest are U.S. Pat. Nos. 3,373,070 and 3,373,071 to Fuerst. The Fuerst technique is to impregnate the decor sheet first with plain melamine resin, and then apply a thick coating to the surface of the impregnated sheet using a relatively viscous mixture of 2,000-60,000 centi-poise.
U.S. Pat. No. 3,975,572 to Power employs an acrylic resin-melamine/formaldehyde resin composition which, like the coating in the Fuerst patents, is applied over the already impregnated decor sheet, after the saturated decor sheet has been dried.
U.S. Pat. No. 4,322,468 to Raghava uses a special coating composition of a fully hydrolyzed polyvinyl alcohol modified melamine-formaldehyde resin.
U.S. Pat. No. 4,713,138 to Ungar et al. discloses a method of providing a paper facing sheet for use as the uppermost sheet in the manufacture of abrasion resistant decorative laminates. The process includes the step of effecting coating and impregnating in essentially one step. According to this patent, the laminated panel has an abrasion resistant composition deposited in an ultra-thin layer.
U.S. Pat. No. 4,880,689 to Park et. al., U.S. Pat. Nos. 4,940,503 and 5,034,272 to Lindgren et al., U.S. Pat. Nos. 5,266,384 and 5,702,806 to O""Dell et al., U.S. Pat. Nos. 5,288,540, 5,362,557, 5,456,949 and 5,558,906 to Albrinck et al., and U.S. Pat. Nos. 5,037,694, 5,093,185 and 5,037,694 to Ungar et al. all disclose decorative laminates and/or processes for preparing decorative laminates.
None of these patents disclose decorative laminates that have abrasion resistant particles with an average particle size from about 9 to about 12 microns and particle concentration of from about 2 to 4 grams per square meter of surface area. Furthermore, none of these patents disclose a process, which involves simultaneously coating: (i) the top surface or side of a dried, partially impregnated paper with an abrasion resistant coat, and (ii) the bottom surface or side of the dried, partially impregnated paper with a thermosetting resin coating. Thus, none of these patents describe the efficient process and construction of the subject low pressure laminated panel.
It is an object of the present invention to provide a process for the manufacture of a high quality, abrasion resistant laminated panel.
It is another object of the present invention to provide such a process in which the panel is preferably a low pressure laminated panel.
It is still another object of the present invention to provide such a process that produces a printed decorative laminated panel or a solid color laminated panel.
It is a further object of the present invention to provide such a process that is less expensive due to less handling required by the process.
It is still further object of the present invention to provide such a process that has simultaneous coating of the top and bottom surfaces of a resin impregnated web.
It is yet a further object of the present invention to provide such a panel in which particles are not applied in the dry state.
These and other objects of the invention are attained by providing a laminated panel having an abrasion resistant surface. The abrasion resistant panel comprises: a single, thermoset resin impregnated web having a first surface and a second surface; an abrasion resistant top coat on the first surface of the thermoset resin impregnated web; a bottom coat of a thermoset resin on the second surface, opposite the first surface, of the thermoset resin impregnated web; a substrate, wherein said substrate is thermally bonded to the thermoset resin impregnated web that is coated; and a resin impregnated bottom or balancing sheet thermo-fused to said substrate on a surface of said substrate opposite the bottom coat.
The above laminated panel having an abrasion-resistant surface is manufactured by a process, comprising: (a) partially impregnating a paper sheet or web with a thermosetting resin, wherein said partial impregnation is carried out so that about 40% to about 60% of the total resin required for full saturation is used; (b) drying the partially impregnated web to a volatile content from about 10% to about 15%, preferably from about 11% to about 13%; (c) coating the top surface or side of the dried, partially impregnated web with an abrasion resistant thermoset resin coat; (d) simultaneously coating the bottom surface or side of the dried, partially impregnated web with a thermosetting resin coat; (e) thermo-fusing the coated web onto a substrate; and (f) simultaneously thermo-fusing a resin impregnated bottom sheet to the other side of the substrate to produce a flat laminated panel. The resin impregnated bottom sheet may be made pursuant to steps (a) through (d) above, or without the abrasion resistant coat.
During simultaneous coating of the top and bottom surfaces, the amount of coating resin used is controlled by metering the amount of resin and abrasion resistant resin coat applied on each surface of the web.
The laminated panel produced in accordance with the present invention has an improved abrasion and scratch resistance.